The present invention relates to the field of heart valves. More particularly, it relates to a valve having a sewing cuff assembly that may be easily and securely coupled to the valve via snap-fitting. In addition, the invention relates to a method for snap-fitting a sewing cuff to a valve.
Prosthetic heart valves are used to replace diseased heart valves in humans. Prosthetic heart valves include mechanical heart valves, bioprosthetic valves, and polymer valves. The term “mechanical valve” as used herein refers to bi-leaflet heart valves comprising a valve orifice fabricated at least in part of a rigid, biologically compatible material such as pyrolytic carbon, and comprising essentially no biological components. The term “bioprosthetic valve” refers to a bi-leaflet or tri-leaflet heart valve comprising at least some biological components such as tissue or tissue components. The biological components of tissue valves are obtained from a donor animal (typically bovine or porcine) or human, and the valve may comprise either biological materials alone or biological materials with man-made supports or stents. The term “polymeric valve” refers to a tri-leaflet, bi-leaflet, or mono-leaflet heart valve comprising at least some elastomeric polymer components, including at least elastomeric polymer valve leaflet(s).
Conventional prosthetic heart valves, whether mechanical, bioprosthetic, or polymer valves, typically include an annular valve body comprising an orifice for blood flow through the valve. The valve body can be made of materials such as biocompatible pyrolitic carbon (mechanical valves), one or more metals or alloys (such as titanium or stellite), porcine or bovine pericardium tissue (bioprosthetic valves), thermoplastics like Delrin or PEEK, or silicone or polyurethane (polymer valves). Leaflets are coupled to the annular body for movement between an open position and a closed position to allow or prevent blood flow through the orifice. Heart valves may include one, two, or three leaflets. The leaflets can be made of pyrolytic carbon, treated tissue, or polymers. The valve is typically attached to a human heart with sutures via a sewing cuff, or some other mechanical attachment means (e.g., staples).
Sewing cuffs generally comprise a toroidal member that is attached to the periphery of the annular valve body to form a site for anchoring sutures to the annulus of the heart during implantation of the heart valve. Sewing cuffs are typically covered with a cloth material, such as polyester, and may also comprise a filler material such as Teflon felt or Dacron cloth. The sewing cuff may be coupled to a peripheral groove on the lower end of the valve body by circumferential cinch-like sutures, or may be mechanically captured adjacent to a stiffening ring.
Existing methods of coupling the sewing cuff to the valve body involve prolonged and repeated handling of the heart valve body. Because attachment of the sewing cuff to the heart valve is a relatively labor-intensive and expensive part of valve fabrication, and because heart valves are more susceptible to damage the more they are handling during assembly, packaging and storage, there is a need for a sewing cuff that can be quickly and securely coupled to the valve body with minimal handling.
There are a number of risks associated with open-heart surgery that are related to the duration of the procedure. Despite advances in blood conservation, the longer it takes to complete a surgical procedure the greater the chance the patient may need a transfusion, which carries with it the risk of transmitting diseases such as HIV or hepatitis, among others. Furthermore, even in the event a procedure is performed successfully, the potential always exists for excessive bleeding over the duration of the procedure, which can result in death of the patient. In addition to problems associated with blood loss and transfusion, a patient connected to a heart-lung machine during a valve replacement procedure may suffer memory loss after surgery. It is therefore desirable to minimize, to the extent possible, the duration of any open heart surgical procedure.
Therefore, there is a need for a heart valve and sewing cuff which can be assembled together with a minimum of handling, and a method for rapidly and securely affixing a sewing cuff to a heart valve. Desirably, the assembled valve would have a low radial thickness of the sewing cuff assembly and a large blood flow orifice area.